wow, thats quite a drop in price, r u sure all the parts are identical? (eg the motherboard is the 400MHz version not the older 333MHz)
Or u could save some money on the motherboard and get a Soltek SL-KT600-R "Purple Ray" (Socket A) Motherboard (MB-007-ST) which is a good deal cheaper and u don't lose much (just the lan cards), u should be able to get it for $100.
Well if the online thing is true or u decide on a cheaper motherboard u can afford the 2600 ;)